Oral composition and abrasive therefor

ABSTRACT

Calcium hydrogenphosphate anhydride is disclosed whose crystallite has an average size of 300 to 3,500 angstroms as measured by X-ray diffractometry, and preferably, which has a density of 2.650 to 2.885 grams per cubic centimeters, a specific surface area of 2.5 to 20 square meters per gram as measured by the BET method, and an average agglomerate diameter of 2 to 30 micronmeters has good physical properties as an abrasive, and that when it is used as an abrasive in an oral composition, the resulting oral composition is improved in cleaning action and in the effect of making the tooth aesthetically white without increasing its abrasiveness.

BACKGROUND OF THE INVENTION

This invention relates to an abrasive for use in oral compositions suchas dentifrices, prophylactic pastes and the like. More particularly,this invention relates to a highly cleaning, low abrading abrasive foruse in oral compositions which consists of calcium hydrogenphosphateanhydride (secondary calcium phosphate anhydride) whose crystallite hasan average size of 300 to 3,500 angstroms as measured by X-raydiffractometry. This invention also relates to an oral compositioncontaining the abrasive.

In general, abrasives for use in oral compositions, for example,dentifrices and prophylactic pastes are required to have an increasedability of efficiently removing away stain, dental plaque, and fooddebris adhered to or deposited on teeth with the aid of physical action,that is, an improved cleanability as a tooth cleaning agent, and toexhibit mild abrasiveness to such an extent that the tooth enamel willnot be damaged, as well as to prevent deposition of dental plaque andcalculus.

In this case, the efficiency of physical removal of stain, plaque, andfood debris can be increased by using an abrasive having increasedabrasiveness. Particularly, it has been a common practice in the priorart to enhance the cleaning effect of an abrasive on the tooth surfaceby increasing the abrasiveness thereof. However, increasing abrasivenessis generally opposite to the prevention of damage to the tooth surface.The higher the abrasiveness, the greater is the likelihood that thetooth surface would be abraded away. Particularly when brushing is doneinadequately, there is the increased likelihood that wedge-shapeddeffects would be formed and the tooth surface would be marred orscratched and reduced in luster. Thus, there is a need for an abrasivefor use in oral compositions which will not cause damage to the toothsurface while retaining a proper degree of abrasiveness and havingimproved cleaning effect.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide anabrasive for use in oral compositions in which cleaning action isimproved without increasing abrading action.

It is another object of the invention to provide an oral compositioncomprising an abrasive having an improved cleaning action withoutincreasing abrading action.

As a result of extensive investigations to meet the above-mentionedneed, the inventors have found that calcium hydrogenphosphate anhydride(secondary calcium phosphate anhydride) whose crystallite has an averagesize of 300 to 3,500 angstroms as measured by X-ray diffractometry, andpreferably, which has a density of 2.650 to 2.885 grams per cubiccentimeters, a specific surface area of 2.5 to 20 square meters per gramas measured by the BET (Brunauer-Emmett-Teller) method, and an averageagglomerate diameter of 2 to 30 micronmeters has good physicalproperties as an abrasive, and that when the above-defined calciumhydrogenphosphate anhydride is used as an abrasive in an oralcomposition, the resulting oral composition is improved in cleaningaction and in the effect of making the tooth aesthetically white withoutincreasing its abrasiveness.

It was difficult in the prior art to enhance the cleaning action and tolower the abrading action of an abrasive at the same time inasmuch asthe cleaning action of conventional abrasives is substantiallyproportional to the abrading action thereof, and it is thus imperativefor cleaning enhancement to increase abrading action. On the contrary tosuch conventional belief, the inventors have found that calciumhydrogenphosphate anhydride having crystallites of a size having anaverage value of 300 to 3,500 angstroms as measured by X-raydiffractometry exhibits improved cleaning action irrespective of its lowabrasiveness as demonstrated in experiments to be described later, andthus, the use of this calcium hydrogenphosphate anhydride alone issufficiently effective to clean up the tooth without impairing thedental enamel, meeting both the requirements of high cleanability andlow abrasiveness at the same time with the additional benefit of makingthe tooth aesthetically white.

It is well known in the art to use calcium hydrogenphosphate anhydride(secondary calcium phosphate anhydride) as an abrasive for dentifricesor the like. However, such previously used calcium hydrogenphosphateanhydride usually has an average crystallite size of 3,800 to 4,300angstroms as measured by X-ray diffractometry, a specific surface areaof about 1 to 2 m² /g as measured by the BET method, and a density of2.890 g/cm³ and has a microscopic-structure (a particle shape) as shownin FIG. 1, and as a result, exhibits too high abrasiveness as shown inexperiments to be described later as long as it is in the form of singleparticle having a normal particle size, that is, a particle diameter of10 to 30 microns. When such conventional calcium hydrogenphosphateanhydride is used alone as an abrasive, the resulting oral compositionwill show an abrasiveness value of above 250, as measured by the RDA(Radio Active Dentin Abrasion) method, which value is generally regardedas the upper limit by the ADA (American Dental Association) and otherdental associations, and thus has the possibility of inducingwedgeshaped defects after long term repeated use if the brushing way isinadequate. For this reason, the conventional calcium hydrogenphosphateanhydride abrasive was used in combination with other mild abrasives. Ascompared with the conventional ones, the calcium hydrogenphosphateanhydride (secondary calcium phosphate anhydride) of the presentinvention has an average crystallite size of 300 to 3,500 angstroms asmeasured by X-ray diffractometry, has less sharp edges or more roundedges, exhibits extremely low abrading action so that it can be used asa sole abrasive, and exhibits more cleaning action (or stain removingaction) than other types of abrasive having a similar degree ofabrasiveness, with the additional benefit of making the toothaesthetically white. These are new findings made by the inventors.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a photomicrograph (3000×magnification) of a prior art calciumhydrogenphosphate anhydride sample;

FIGS. 2 to 5 are photomicrographs of calcium hydrogenphosphate anhydridesamples of the present invention, each of the photomicrographs of FIGS.2 to 4 having a magnification of 3000 and the photomicrographs of FIG. 5having a magnification of 2000,

FIG. 6 schematically illustrates a spherulitic calcium hydrogenphosphateanhydride crystal according to the present invention; and

FIGS. 7 to 10 are diagramatic illustrations of the abrasiveness vs. thecleanability of various calcium hydrogenphosphate samples, respectively.

DETAILED DESCRIPTION OF THE INVENTION

The abrasive for use in oral compositions according to the presentinvention consists of calcium hydrogenphosphate anhydride (secondarycalcium phosphate anhydride) whose crystallite has an average size (alsoreferred to as "average crystallite size" herein) of 300 to 3,500angstroms as measured by X-ray diffractometry as will be demonstrated inthe experiment shown below, and which has a microscopic structure asshown in FIGS. 2-5. Because of its crystalline attributes, the calciumhydrogenphosphate anhydride of the invention exhibits a moderate degreeof abrasiveness and a high degree of cleaning to the tooth, and at thesame time, is effective for making the tooth aesthetically white.

The calcium hydrogenphosphate anhydride which is useful in the presentinvention has an average crystallite size of 300 to 3,500 angstroms,with one having an average crystallite size of 300 to 3,000 angstromsbeing particularly preferred for improved cleaning action. If theaverage crystallite size is less than 300 angstroms, the phosphate showstoo low cleaning action, and if the average crystallite size is morethan 3,500 angstroms, the phosphate shows too high abrasiveness, bothfailing to achieve the objects of the invention.

Preferably, the calcium hydrogenphosphate anhydride useful in thepresent invention has a density of 2.650 to 2.885 g/cm³, more preferably2.750 to 2.885 g/cm³ at 20° C., a specific surface area of 2.5 to 20 m²/g, more preferably 3 to 10 m² /g as measured by the BET method, and anaverage agglomerate diameter of 2 to 30 microns, more preferably 5 to 25microns as measured by the laser light-scattering photometry, and has amicroscopic structure as shown in FIGS. 2 to 5.

The conventional prior art calcium hydrogenphosphate anhydride has anaverage crystallite size of 3,800 to 4,300 angstroms, a density of 2.890g/cm³ at 20° C., a specific surface area of about 1 to 2 m² /g asmeasured by the BET method, and a microscopic structure as shown in FIG.1, and thus exhibits too high abrasiveness as shown in experiments to bedescribed later as long as it is in the form of single particle having anormal particle diameter of 10 to 30 microns. When such conventional oneis used alone as a sole abrasive, the resulting oral composition willshow an abrasiveness value of above 250 as measured by the RDA methodand thus may induce wedge-shaped defects after long term repeated use ifthe brushing way is inadequate. On the other hand, the calciumhydrogenphosphate anhydride of the present invention having an averagecrystallite size, a density, specific surface area and averageagglomerate size within the above-defined ranges exhibits extremelyreduced abrading action as compared with the conventional ones so thatit can be used alone as a sole abrasive for oral compositions, and atthe same time, exhibits more cleaning action or stain removing actionthan other types of abrasive having a similar degree of abrasiveness andis very effective for making the tooth aesthetically white. It should benoted that the calcium hydrogenphosphate anhydride of the inventiontends to increase its specific surface area and reduce its density asits average crystallite size is reduced.

The term "density" used herein is a measurement using a pycnometerfollowed by calculation according to the following formula: ##EQU1##where M_(S) : the weight of the pycnometer plus the weight of a powdersample,

M_(O) : the weight of the pycnometer,

M_(L) : the weight of the pycnometer filled with liquid (water),

M_(SL) : the weight of the pycnometer filled with a powder sample andfurther with liquid (water), that is, [pycnometer weight+powderweight+liquid weight],

ρ_(L) : the density of the liquid (water) at 20° C., and

ρ_(P) : the density of the powder at 20° C.

The calcium hydrogenphosphate anhydride useful herein is preferably inthe form of a cohesive aggregate of plate crystals whose primaryparticle has an average particle size of 0.1 to 5 microns and which hasa microscopic structure as shown in FIGS. 2-4. This is preferred for thefollowing reason. In general, oral compositions, for example,dentifrices are preferably required to have improved juice effect,little change the taste of food, and give a pleasant feel to the mouth.To this end, for instance, it has been proposed to addN-alkyloylsarcosinates such as sodium N-lauroylsarcosinate to oralcompositions to enhance the juice effect, or to substitute α-olefinsulfonates for alkyl sulfates. However, the addition ofN-alkyloylsarcosinates has some problems, for example, the amount of thecompound added is restricted to 0.5% by weight or less in view of mucousmembrane separation. There is a need for an abrasive which whenincorporated in oral compositions, can increase the juice effect andimprove the mouth feel. It has been found that the calciumhydrogenphosphate anhydride of the present invention in the form ofcohesive aggregate of plate crystals whose primary particle has anaverage particle size of 0.1 to 5 microns can, when used as such anabrasive for oral compositions, increase the cleaning action of thecompositions without increasing the abrading action, so that an improvedoral composition is obtained which causes little scratch to the dentalenamel and has excellent juice effect and a pleasant feel to the mouth.The average value of the size of primary particles is obtained from ameasurement on an electron micrograph followed by calculation. Theabove-defined calcium hydrogenphosphate anhydride has a microscopicstructure as shown in FIGS. 2 to 4, that is, a structure in which plateor flake crystals aggregate or closely stack one on top of another likea pine cone to form a cohesive body with or without microfine particlesof indefinite crystalline structure.

The calcium hydrogenphosphate anhydride useful in the present inventionmay also include a spherulitic calcium hydrogenphosphate anhydride asshown in FIG. 5. This spherulitic calcium hydrogenphosphate anhydride iscomparable in cleaning action to conventional abrasives having anabrasivity on copper plate of about 20 to 30 mg when it has anabrasivity on copper plate of about 1 to 5 mg, and to other conventionalabrasives having the abrasivity of about 30 to 50 mg when it has theabrasivity of about 5 to 20 mg, as will be seen in experiments to bedescribed later. In addition to such a unique combination of lowabrasiveness with high cleanability, the spherulitic calciumhydrogenphosphate anhydride has an improved lustering effect so thatsufficient luster is imparted to the tooth surface even when it is usedalone as an abrasive. As compared with oral compositions containing aconventional subangular calcium hydrogenphosphate anhydride abrasiveconsisting of a mixture of plate, prism and needle crystals, oralcompositions containing this spherulitic calcium hydrogenphosphateanhydride give little gritty feel to the oral cavity, is mild to theoral membrane, and thus give a pleasant feel to the mouth. Namely, theuse of spherulitic calcium hydrogenphosphate anhydride can meet therequirements of high cleanability, low abrasiveness, high lustering, andpleasant feel at the same time. The conventional prior art calciumhydrogenphosphate anhydride having an average agglomerate size of 10 to30 microns is of a subangular shape as shown in FIG. 1 and has aroundness of about 0.4 and a specific surface area of about 1 to 2 m² /gas measured by the BET method, and thus exhibits too high abradingaction as shown in experiments to be described later as long as it is inthe form of agglomerates having a normal particle size. When suchconventional one is used alone as a sole abrasive, the resulting oralcomposition will show an abrasion value of above 250 as measured by theRDA method and thus may induce wedge-shaped defects after long termrepeated use, as described above. On the other hand, the spheruliticcalcium hydrogenphosphate anhydride of the present invention exhibitsincreased cleaning action irrespective of reduced abrasiveness and iseffective for imparting luster to the tooth surface at the same time.

The spherulitic calcium hydrogenphosphate anhydride used hereinpreferably has an average roundness of 0.45 to 0.95, more preferably 0.5to 0.9. The roundness is obtained from a photomicrograph and given by##EQU2## where R is the radius of the maximum inscribed circle, r_(n) isthe radius of curvature of an n-th edge of a powder particle, and N isthe number of measurements of r. One roundness measurement is shown inFIG. 6 in which an exemplary particle is illustrated with R, r₁, r₂, r₃,and r₄. The more round the shape, the more approximate to one theroundness is. For further information, reference should be made toWadell, J., Geol., 40 (1932), 443-451. Also preferably, the spheruliticcalcium hydrogenphosphate anhydride is one containing at least 70% ofcalcium hydrogenphosphate crystals as analyzed by X-ray diffractometry.

The calcium hydrogenphosphate anhydride of the present invention may beprepared in a conventional way, for example, by adding in theneutralizing reaction between phosphoric acid and lime milk acrystallization modifier capable of controlling the growth of crystalsor effecting on crystal growth-kinetics, crystal habit and specificgrowth rates of individual crystal faces, as disclosed in U.S. Pat. Nos.2,287,699 (1942), 3,012,852 (1961), 3,066,056 (1962), and 3,169,096(1965), and Japanese Patent Publication Nos. 39-3272 and 39-3273 (1964).In this case, the crystallization modifiers used may preferably bephosphoric acid condensates and salts thereof, and be added in thecourse of neutralizing rection between phosphoric acid and lime milk.Also preferably, the amount of the crystallization modifier added rangesfrom 0.1 to 40% by weight, more preferably from 0.5 to 30% by weightbased on the weight of the calcium hydrogenphosphate anhydride produced.As the amount of the modifier added increases, the growth of crystals isretarded and the size of crystallites becomes smaller. If the amount ofthe modifier added is less than 0.1% by weight, then crystallites willgrow larger beyond the average size of 3,500 angstroms and result inincreased abrasiveness. If the amount of the modifier added is more than40% by weight, then crystallites will become smaller below the averagesize of 300 angstroms and will not exhibit low abrasion and highcleaning performance. The calcium hydrogenphosphate anhydride of thepresent invention may be prepared in a variety of grades by properlycontrolling the amount of the crystallization modifier added, the pointand rate of addition of the modifier, phosphoric acid concentration,reaction temperature, reaction time, agitation speed and otherparameters in the preparation procedure.

For instance, the calcium hydrogenphosphate anhydride of the presentinvention may preferably be prepared by reacting a calcium compoundhaving an an electrolyte admixed therewith and a phosphoric acidcompound at a temperature of 50° to 90° C. while adding a condensatedphosphate to the reaction mixture.

The abrasive of the present invention may find uses in oral compositionsincluding dentifrices such as toothpastes and powder dentifrices, andprophylactic pastes.

In these applications, the oral compositions having the abrasive of thepresent invention blended therein may contain any desired otheringredients depending on the type of the compositions and the like.

In the case of a dentifrice composition, for example, the calciumhydrogenphosphate anhydride (secondary calcium phosphate anhydride)abrasive of the present invention may be used alone or in admixture withany other conventional abrasives, for example, calcium hydrogenphosphatedihydrate, conventional calcium hydrogenphosphate anhydride having anaverage crystallite size of 3,800 to 4,300 angstroms (falling outsidethe scope of the invention), calcium carbonate, calcium pyrophosphate,insoluble sodium metaphosphate, amorphous silica, crystalline sillica,precipitated silica, aluminosilicate, aluminum oxide, aluminumhydroxide, microcrystalline cellulose, resin, magnesium tertiaryphosphate, magnesium carbonate, etc. and mixtures thereof. When thecalcium hydrogenphosphate anhydride of the present invention is combinedwith another abrasive or abrasives, the amount of the present phosphateused may preferably range from 5 to 100% by weight, more preferably from10 to 100% by weight of the combined abrasives for taking thesubstantial advantage of the present phosphate.

In preparing oral compositions using the abrasive of the presentinvention, there may be blended any conventional ingredients, forexample, binders such as sodium carboxymethyl cellulose, hydroxyethylcellulose, alginates, carrageenan, gum arabic, polyvinyl alcohol, etc.;humectants such as polyethylene glycol, sorbitol, glycerin, propyleneglycol, etc.; foaming agents such as sodium lauryl sulfate, sodiumdodecylbenzenesulfonate, sodium hydrogenated coconut fatty acidmonoglyceride monosulfate, sodium lauryl sulfoacetate, sodiumN-lauroylsarcosinate, N-acylglutamates, lauroyl diethanolamide, sucrosefatty acid esters, etc.; flavoring agents, for example, essential oilssuch as peppermint oil, spearmint oil, etc. and flavors such asl-menthol, carvone, eugenol, anethol, etc.; sweeteners such as sodiumsaccharin, stevioside, neohesperidyl dihydrochalcone, glycyrrhizin,perillartine, p-methoxycinnamic aldehyde, somatine, etc.; preservatives;and pharmaceutical agents such as lysozyme chloride, dextranase,bacteriolytic enzymes, mutanase, chlorohesidine and salts thereof,sorbic acid, alexidine, hinokitiol, cetyl pyridinium chloride, alkylglycines, alkyl diaminoethyl glycine salts, allantoin, ε-aminocaproicacid, tranexamic acid, azulene, vitamin E, sodium monofluorophosphate,sodium fluoride, stannous fluoride, water-soluble primary and secondaryphosphoric acid salts, quaternary ammonium compounds, sodium chloride,etc. In preparing oral compositions using the abrasive of the presentinvention, magnesium tertiary phosphate is desirably blended therein toprevent pH lowering and hardening of the oral composition to therebyrender the system more stable, preferably in an amount of 0.1 to 5% byweight, more preferably 0.5 to 3% by weight of the composition.

In an oral composition such as a dentifrice composition, the content ofthe abrasive may be in the range of 5 to 95% by weight, preferably 10 to90% by weight of the composition. The content of the binder may be inthe range of 0.1 to 5% by weight, preferably 0.3 to 3% by weight of thecomposition. The content of the humectant may be in the range of 1 to70% by weight, preferably 10 to 60% by weight of the composition. Thecontent of the foaming agent may be in the range of 0.1 to 10% byweight, preferably 0.2 to 5% by weight of the composition. The contentof the flavor may be in the range of 0.1 to 5% by weight, preferably 0.3to 2% by weight of the composition. The content of the sweetner may bein the range of 0.001 to 5% by weight, preferably 0.005 to 2% by weightof the composition.

The abrasive for use in oral compositions according to the presentinvention, which consists of calcium hydrogenphosphate anhydride whosecrystallite has an average size of 300 to 3,500 angstroms as measured byX-ray diffractometry, exhibits a moderate degree of abrasion to thetooth as well as a high degree of cleaning action and is highlyeffective for making the tooth aesthetically white. Differently stated,since the calcium hydrogenphosphate anhydride having an averagecrystallite size within the above-defined range exhibits more cleaningaction than other abrasives having the same degree of abrasion, it canclean off stain, plaque and food debris deposited to the tooth withoutdamage to the tooth surface. The calcium hydrogenphosphate anhydridehaving an average crystallite size of 300 to 3,500 angstroms issignificantly low in abrasiveness as compared with the conventionalprior art calcium hydrogenphosphate anhydride having an averagecrystallite size of 3,800 to 4,300 angstroms, and thus it is notnecessarily required to combine the former with other abrasives asrequired for the latter, that is, the former can be used alone as a soleabrasive for oral compositions.

An oral composition of the invention is prepared by blending the calciumhydrophosphate anhydride abrasive into an oral composition or mixing itwith the other ingredients.

In order that those skilled in the art will more readily understand theinvention, some exemplary procedures for preparing the calciumhydrogenphosphate anhydride of the invention will be presented below.

Preparation 1

Lime water is prepared by heating 3 liters of an aqueous solution having4.0 grams of magnesium chloride dissolved therein to 80° C., pouring 380grams of quick lime into the solution with stirring, and continuingstirring for 30 minutes to allow the quick lime to be slaked. Thereaction mixture is passed through 100 mesh screen to remove coarseparticles, obtaining lime water having a converted concentration of 124grams of calcium oxide per liter.

Then, one liter of an aqueous solution of 75% phosphoric acid is heatedto 75° C., and the above-prepared lime water is added to the solution ata rate of 600 milliliters/hour with stirring. At the point when the pHvalue of the reaction mixture has reached 2.2, pyrophosphoric acidhaving a P₂ O₅ content of 80% is additionally added at a rate of 0.3grams/minute concurrently with the addition of lime water. When the pHvalue has reached 2.8, the addition of pyrophosphoric acid isterminated. The addition of lime water is further continued until the pHvalue of the reaction solution reaches 5.0. The reaction solution isthen filtered, and the filter cake is washed with water and dried at 60°C. for 24 hours. It was found that by varying the amount of apolyphosphoric acid or its salt, such as pyrophosphoric acid or sodiumpyrophosphate added and controlling the starting point and rate ofaddition of a polyphosphoric acid or its salt, there can be obtainedcalcium hydrogenphosphate anhydride having correspondingly varyingcrystallite size, density and specific surface area.

Preparation 2

Lime water is prepared by heating 3 liters of an aqueous solution having3.7 grams of magnesium chloride dissolved therein to 80° C., pouring 390grams of quick lime into the solution with stirring, and continuingstirring for 30 minutes to allow the quick lime to be slaked. Thereaction mixture is passed through the 100 mesh screen to remove coarseparticles, obtaining lime water having a converted concentration of 128grams of calcium oxide per liter.

Then, one liter of an aqueous solution of 75% phosphoric acid is heatedto 78° C., and the above-prepared lime water is added to the solution ata rate of 570 milliliters/hour with stirring. At the point when the pHvalue of the reaction mixture has reached 0.8, pyrophosphoric acid isadditionally added concurrently with the addition of lime water. Whenthe pH value has reached 1.2, the addition of pyrophosphoric acid isterminated. The addition of lime water is further continued until the pHvalue of the reaction solution reaches 5. The total amount of lime wateradded is 5.3 liters, and the amount of pyrophosphoric acid added is 13.5grams. This means that pyrophosphoric acid is added in an amount of 2.0parts by weight per 100 parts by weight of calcium oxide. The reactionsolution is then filtered, and the filter cake is washed with water anddried at 60° C. for 24 hours, obtaining calcium hydrogenphosphateanhydride within the scope of the present invention.

Preparation 3

Lime water is prepared by heating 3 liters of an aqueous solution having3.4 grams of magnesium chloride dissolved therein to 80° C., pouring 393grams of quick lime into the solution with stirring, and continuingstirring for 30 minutes to allow the quick lime to be slaked. Thereaction mixture is passed through the 100 mesh screen to remove coarseparticles, obtaining lime water having a converted concentration of 129grams of calcium oxide per liter.

Then, one liter of an aqueous solution of 70% phosphoric acid is heatedto 80° C., and the above-prepared lime water is added to the solution ata rate of 540 milliliters/hour with stirring. At the point when the pHvalue of the reaction mixture has reached 0.4, pyrophosphoric acid isadditionally added concurrently with the addition of lime water. Whenthe pH value of 1.0 is reached, the addition of pyrophosphoric acid isterminated. The addition of lime water is further continued until the pHvalue of the reaction solution reaches 5.0.

The total amount of lime water added is 5.2 liters, and the amount ofpyrophosphoric acid added is 13.0 grams. This means that pyrophosphoricacid is added in an amount of 1.94 parts by weight per 100 parts byweight of calcium oxide.

The product is filtered and dried in a conventional manner, obtainingcalcium hydrogenphosphate anhydride falling within the scope of thepresent invention.

It was found that by controlling the starting point and rate of additionof pyrophosphoric acid, there can be obtained calcium hydrogenphosphateanhydride having varying degree of cleaning action.

Preparation 4

Lime water is prepared by heating 5 liters of water to 70° C., pouringabout 650 grams of quick lime into the water, and continuing stirringfor 30 minutes. The resulting lime water has a converted concentrationof about 130 grams of calcium oxide per liter. Using the 100 meshscreen, coarse particles are removed from the lime water.

Then, one liter of an aqueous solution of 50% phosphoric acid having apyrophosphate added thereto is heated to 73° C., and the above-preparedlime water is added to the solution at a rate of 1 liter/hour withstirring. At the end of reaction, the reaction solution is filtered,washed with water, and dried at 60° C. for about 24 hours, obtainingcalcium hydrogenphosphate anhydride in spherulitic form.

It was found that by controlling the amount of the pyrophosphate addedand other parameters, the roundness of the product can be controlled tothe desired level.

Examples are presented below in order to illustrate the effects of theabrasive of the present invention.

EXAMPLE 1

A number of calcium hydrogenphosphate samples having different averagecrystallite sizes and average agglomerate diameters shown in Tables 1and 2 were tested for abrasiveness and cleanability by the followingmethods, in order to examine the correlation between size andperformance of abrasives. The calcium hydrogenphosphate anhydridesamples used had a specific surface area of 2.5 to 20 m² /g as measuredby the BET method, and a density of 2.650 to 2.885 g/cm³. The resultsare shown in Table 3.

The average crystallite size is measured by carrying out X-raydiffraction analysis on a powder sample. Based on the broadening ofpeaks, the crystallinity of the powder sample is quantitativelyexpressed using the size of crystallites as an index. Cu-Kα ray is usedfor measurement as the X-ray source, and the data of X-ray diffractionare analyzed for non-overlapping predominant peaks using Scherrer'sequation D=Kλ/β cos θ, determining the average size of crystallites. Inthis case, the predominant peaks selected are 2θ=53.1°, 49.3°, 47.3°,36.1°, 32.9°, 32.6°, 31.1°, 30.25°, 28.65°, and 13.15°, and they areaveraged. In the above equation, D is the size of a crystallite (inangstrom), λ is the wavelength of X-ray used for measurment (inangstrom), β is the spread of diffracted rays purely based on the sizeof crystallites (in radian) (the reference used is an α-Al₂ O₃ powderfired at 1,100° C. for 24 hours), K is shape factor (constant, 0.9 inthis measurement), and θ is the Bragg angle of diffracted rays. It is tobe noted that β is an experimentally determined half-value-width minusthe half-value-width of a highly crystalline material measured under thesame conditions.

Abrasiveness Measurment

The RDA (Radioactive Dentin Abrasion) value was measured according tothe process described in Hefferen, J. Dent. Res., Vol. 55, No. 4, pp.563-573.

Cleanability Measurement

Tobacco tar was collected in a conventional manner and dissolved in asuitable solvent. The tar solution was uniformly coated onto a tile anddried by heating. The tar-coated tile was placed in a polishing tank andbrushed 2,000 times under a load of 200 grams using a suspension of 5grams of a powder (each calcium hydrogenphosphate sample shown in Tables1 and 2) in 15 grams of an aqueous solution of 60% glycerin containing0.3% of sodium carboxymethyl cellulose. At the end of polishing, thetile was visually observed to determine the percent removal of tartherefrom.

The brush used is a commercially available tooth brush having 44 bundlesof bristles, a bristle diameter of 8 mils (about 0.2 mm), and a bristlelength of 12 mm, made of nylon-62, with the brush hardness designated M(medium) according to the Japanese household product quality indication.

    ______________________________________                                        Evaluation criterion for tar removal                                                     Percentage removal of                                              Point      tobacco tar                                                        ______________________________________                                        1           0-10%                                                             2          11-20%                                                             3          21-30%                                                             4          31-40%                                                             5          41-50%                                                             6          51-60%                                                             7          61-70%                                                             8          71-80%                                                             9          81-90%                                                             10          91-100%                                                           ______________________________________                                    

                  TABLE 1                                                         ______________________________________                                        DCP-D (calcium hydrogenphosphate dihydrate)                                         Average                                                                       crystallite                                                                              Average agglomerate                                          Sample                                                                              size (Å)                                                                             diameter* (μm)                                            ______________________________________                                        No. 1 --          9              Comparison                                   No. 2 --         14              Comparison                                   ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        DCP-A (calcium hydrogenphosphate anhydride)                                          Average                                                                       crystallite                                                                              Average agglomerate                                         Sample size (Å)                                                                             diameter* (μm)                                           ______________________________________                                        No. 3  4150         2**          Comparison                                   No. 4  4150       16             "                                            No. 5   282       13             "                                            No. 6  3810       18             "                                            No. 7   375       22             Invention                                    No. 8   661       10             "                                            No. 9   867        7             "                                             No. 10                                                                              1660       13             "                                             No. 11                                                                              2070       15             "                                             No. 12                                                                              3194       10             "                                            ______________________________________                                         *The average agglomerate diameter was measured using a particle size          distribution measuring instrument, Microtrac (trade name, available from      Leed & Northrup Company).                                                     **obtained by sieving conventional DCPA and collecting a fraction having      an average agglomerate diameter of 2 microns                             

                  TABLE 3                                                         ______________________________________                                        Abrasiveness and cleanability of various                                      calcium hydrogenphosphate samples                                                               Abrasive-                                                             Mixing  ness       Clean-                                           Sample    ratio   (RDA value)                                                                              ability                                          ______________________________________                                        DCP-D No. 1                                                                             --       50        2.4    Comparison                                DCP-D No. 2                                                                             --       57        2.6    "                                         DCP-A No. 3                                                                             --      135        4.3    "                                         DCP-A No. 4                                                                             --      ≧250                                                                              7.3    "                                         DCP-D No. 2/                                                                            8/2     140        4.5    "                                         DCP-A No. 4                                                                   DCP-D No. 2/                                                                            5/5     218        6.0    "                                         DCP-A No. 4                                                                   DCP-A No. 5                                                                             --      125        3.2    "                                         DCP-A No. 6                                                                             --      ≧250                                                                              6.8    "                                         DCP-A No. 7                                                                             --      118        4.9    Invention                                 DCP-A No. 8                                                                             --      145        6.1    "                                         DCP-A No. 9                                                                             --      134        5.3    "                                         DCP-A No. 10                                                                            --      155        6.3    "                                         DCP-A No. 11                                                                            --      151        6.8    "                                         DCP-A No. 12                                                                            --      180        7.5    "                                         DCP-D No. 2/                                                                            5/5     153        6.1    "                                         DCP-A No. 10                                                                  DCP-D No. 2/                                                                            9/1      86        4.0    "                                         DCP-A No. 11                                                                  DCP-D No. 2/                                                                            5/5     141        6.5    "                                         DCP-A No. 11                                                                  DCP-D No. 2/                                                                            5/5     101        5.0    "                                         DCP-A No. 8                                                                   ______________________________________                                    

The abrasiveness (RDA value) of the samples shown in Table 3 is plottedrelative to the cleanability in FIG. 7. The reference numerals in FIG. 7corresponds to sample Nos. in Table 3. Those reference numerals within acircle are samples of the present invention.

As seen from the data of Table 3 and FIG. 7, calcium hydrogenphosphateanhydride samples having an average crystallite size of 300 to 3,500angstroms exhibits a high degree of cleaning action irrespective of lowabrasiveness. In the case of calcium hydrogenphosphate dihydrate samplesand calcium hydrogenphosphate anhydride samples having an averagecrystallite size outside the above-defined range, cleanability isproportional to abrasiveness, and thus, abrasiveness must be increasedto enhance cleanability.

EXAMPLE 2

The following clinical test was carried out to demonstrate how adentifrice containing the calcium hydrogenphosphate anhydride abrasiveof the invention is effective for making the tooth aesthetically white.

Using three abrasives, A [DCP-D No. 2/DCP-A No. 11 (5/5)], B [DCP-D No.2/DCP-A No. 4 (8/2)], and C [DCP-D No. 2/DCP-A No. 4 (5/5)], allappearing in Table 3, toothpastes were prepared having the followingformulation.

    ______________________________________                                        Abrasive             50.0%                                                    Propylene glycol    2.0                                                       Glycerin            20.0                                                      Sodium saccharin    0.2                                                       Sodium carboxymethyl cellulose                                                                    0.7                                                       Carrageenan         0.2                                                       Colloidal silica    1.0                                                       Sodium lauryl sulfate                                                                             1.5                                                       Flavors             1.0                                                       Preservatives       trace amount                                              Water               balance                                                                       100.0% by weight                                          ______________________________________                                    

It is to be noted that in these abrasives, sample DCP-A No. 11 has aspecific surface area of 5.1 m² /g and a density of 2.875 g/cm³, sampleDCP-A No. 4 has a specific surface area of 1.2 m² /g and a density of2.890 g/cm³, and sample DCP-D No. 2 has a specific surface area of 1.1m² /g and a density of 2.32 g/cm³.

A panel consisted of 15 specialized members, and they brushed the toothover 4 weeks using these toothpastes. The degree of stain on the toothwas evaluated before and after this 4-week brushing according to thefollowing criterion. The results are shown in Table 4.

    ______________________________________                                        Teeth selected for evaluation                                                 ______________________________________                                        Anterior, labial, upper-lower,                                                                      12 teeth                                                right-left, Nos. 1-3                                                          Anterior, lingual, lower, Nos. 1-3                                                                   6 teeth                                                Total                 18 teeth                                                ______________________________________                                        Evaluation criterion for tooth stain                                          ______________________________________                                        (I) Area of stains adhered per tooth                                          Point             Percent area                                                ______________________________________                                        0                  0%                                                         1                  0% < n ≦ 10%                                        2                 10% < n ≦ 20%                                        .                 .                                                           .                 .                                                           .                 .                                                           9                 80% < n ≦ 90%                                        10                90% < n ≦ 100%                                       ______________________________________                                        (II) Stain density                                                            Point             Color                                                       ______________________________________                                        1                 yellow                                                      2                 brownish yellow                                             3                 brown                                                       ______________________________________                                    

The original yellow of the tooth itself was neglected in this staindensity evaluation.

Using these criteria, the degree of stain on teeth was evaluated interms of (I) multiplied by (II) for each tooth. It will be readilyunderstood that for each tooth, the worst point is 10×3=30 points. Theresult for each toothpaste is expressed as an average value per tooth.

                  TABLE 4                                                         ______________________________________                                        Degree of stain            Percent                                            Abrasive                                                                              Initial     After 4 week brushing                                                                        removal                                    ______________________________________                                        A       1.86   points   1.55   points   20.0%                                 B       1.99            1.73           13.1                                   C       2.01            1.85            8.0                                   ______________________________________                                    

As seen from the results of Table 4, the abrasive of the presentinvention, that is, abrasive A has improved whitening effectirrespective of low abrasiveness.

EXAMPLE 3

Another clinical test was carried out to demonstrate how a dentifricecontaining the calcium hydrogenphosphate anhydride abrasive of theinvention is effective for making the tooth aesthetically white.

Using abrasives shown in Table 5 having substantially equal abrasivenessin order to avoid that differential abrasion might affect the evaluationof the whitening effect, toothpastes having the following formulationwere prepared.

    ______________________________________                                        Abrasive             42.0%                                                    Propylene glycol    2.0                                                       Sorbitol            25.0                                                      Sodium saccharin    0.1                                                       Sodium carboxymethyl cellulose                                                                    1.1                                                       Colloidal silica    2.0                                                       Sodium lauryl sulfate                                                                             1.5                                                       Flavors             1.0                                                       Preservatives       trace amount                                              Water               balance                                                                       100.0% by weight                                          ______________________________________                                    

                                      TABLE 5                                     __________________________________________________________________________                    Average                                                                              Average     Specific                                                   agglomerate                                                                          crystallite surface                                                                            Abrasivity on                         Abrasive        diameter                                                                             size  Density                                                                             area copper plate                          __________________________________________________________________________    D:                                                                              calcium hydrogenphosphate                                                                   13.6 μm                                                                           430Å                                                                            2.73 g/cm.sup.3                                                                     17 m.sup.2 /g                                                                      1.1 mg                                  anhydride sample No. 13                                                     E:                                                                              calcium hydrogenphosphate                                                                   16.0 μm                                                                           200Å                                                                            2.60 g/cm.sup.3                                                                     28 m.sup.2 g                                                                       1.3 mg                                  anhydride sample No. 14                                                     F:                                                                              calcium hydrogenphosphate                                                                   15.6 μm                                                                           --    --    --   1.4 mg                                  dihydrate sample No. 15                                                     __________________________________________________________________________     Note:                                                                         Abrasivity on copper plate was measured in the same manner as in Example      shown later.                                                             

A number of smokers who had brushed their teeth with an abrasive-freedentifrice for one month and thus had their teeth stained wereclassified into three panels such that each panel consisted of 14smokers and the average value of stain was substantially the same amongthe panels. They brushed for a further three weeks with the toothpasteof the above-mentioned formulation. The stain of teeth was evaluatedbefore and after the tooth stain, five examiners examined the front andrear surfaces of upper two and lower two anteriors in accordance withthe following criterion. The stain was expressed as an average point pertooth for each panel member

    ______________________________________                                        Point         Stain                                                           ______________________________________                                        0             no stain                                                        1             the area of stain adhered is less                                             than 1/3 of the total tooth surface                             2             the area of stain adhered is more                                             than 1/3 of the total tooth surface                             3             the area of stain adhered is more                                             than 2/3 of the total tooth surface                             ______________________________________                                    

The results are shown in Table 6. The results are expressed as anaverage value for each panel.

                  TABLE 6                                                         ______________________________________                                        Abrasive Before use    After use                                                                              Difference                                    ______________________________________                                        D        1.65          0.90     0.75                                          E        1.70          1.56     0.14                                          F        1.68          1.55     0.13                                          ______________________________________                                    

The data of Table 6 prove that the abrasive of the invention, that is,abrasive D has improved whitening effect.

EXAMPLE 4

Calcium hydrogenphosphate samples having different densities andspecific surface areas shown in Table 7 were examined for abrasivenessand cleanability by the following procedure in order to establish thecorrelation between performance and physical properties. The results arealso shown in Table 7. The density was obtained by a measurement using apycnometer followed by calculation as previously described.

Abrasiveness measurement

Using a suspension of 5 grams of a powder (each calciumhydrogenphosphate sample shown in Table 7) in 15 grams of an aqueoussolution of 60% glycerin containing 0.3% of sodium carboxymethylcellulose, a copper plate having a Vickers hardness of 120 as prescribedin Japanese Industrial Standard H-3361 was brushed 20,000 times for 2hours under a load of 200 grams in a horizontal abrasion tester. Thebrush used was the same as used in Example 1. The abrasivity on thecopper plate was measured in milligram.

Cleanability measurement

Cleanability was determined in the same manner as in Example 1.

                                      TABLE 7                                     __________________________________________________________________________                                    Specific                                                                           Abrasivity                                       Average Mixing                                                                             Average    surface                                                                            on copper                                        agglomerate                                                                           ratio by                                                                           crystallite                                                                         Density                                                                            area**                                                                             plate Clean-                             Sample* diameter (μm)                                                                      weight                                                                             size (Å)                                                                        (g/cm.sup.3)                                                                       (m.sup.2 /g)                                                                       (mg)  ability                            __________________________________________________________________________    DCP-D No. 1                                                                            9      --   --    2.320                                                                              --   0.8   2.3 Comparison                     DCP-D No. 2                                                                           14      --   --    2.320                                                                              --   1.2   2.5 "                              DCP-A No. 3                                                                             2***  --   4150  2.890                                                                              4.4  17.3  4.3 "                              DCP-A No. 4                                                                           16      --   4150  2.890                                                                              1.2  47.0  7.3 "                              DCP-D No. 2/    8/2  --    --   --   18.5  4.5 "                              DCP-A No. 4                                                                   DCP-D No. 2/    5/5  --    --   --   31.4  6.0 "                              DCP-A No. 4                                                                   DCP-A No. 16                                                                          25      --    230  2.615                                                                              28.6 1.3   2.9 "                              DCP-A No. 17                                                                          15      --    830  2.706                                                                              13.2 1.5   5.6 Invention                      DCP-A No. 18                                                                          10      --   1600  2.810                                                                              8.9  4.7   5.9 "                              DCP-A No. 19                                                                          13      --   2850  2.861                                                                              3.0  11.3  6.6 "                              DCP-A No. 20                                                                          18      --   3050  2.882                                                                              2.5  20.1  6.9 "                              DCP-D No. 2/    8/2  --    --   --   5.1   5.0 "                              DCP-A No. 19                                                                  DCP-D No. 2/    5/5  --    --   --   10.0  6.3 "                              DCP-A No. 19                                                                  __________________________________________________________________________     *DCP-D is calcium hydrogenphosphate dihydrate and DCPA is calcium             hydrogenphosphate anhydride.                                                  **measured by the BET method.                                                 ***obtained by sieving conventional DCPA and collecting a fraction having     an average agglomerate diameter of 2 microns.                            

The abrasivity on copper plate of each sample shown in Table 7 isplotted relative to the cleanability in FIG. 8. The reference numeralsin FIG. 8 correspond to the sample Nos. in Table 7. Those referencenumerals surrounded by a circle are samples within the scope of theinvention.

As seen from the data of Table 7 and FIG. 8, calcium hydrogenphosphateanhydride samples having an average crystallite size of 300 to 3,500angstroms, a density of 2.650 to 2.885 g/cm³, and a specific surfacearea of 2.5 to 20 m² /g exhibit abrasiveness and cleanability mutuallyindependently, that is, exhibit increased cleanability irrespective oflow abrasiveness, and are comparable in cleaning action to conventionalabrasives having an abrasivity of about 20 to 30 mg when they have anabrasivity of about 1 to 5 mg, and to conventional abrasives having anabrasivity of about 30 to 50 mg when they have an abrasivity of about 5to 20 mg. It was also found that similar effects were achieved bymixtures of calcium hydrogenphosphate anhydride samples havingcrystallite size, density and specific surface area within the presentlydefined ranges with calcium hydrogenphosphate dihydrate samples. In thecase of calcium hydrogenphosphate anhydride samples having crystallitesize, density and specific surface area outside the presently definedranges, calcium hydrogenphosphate dihydrate samples, and mixturesthereof, cleanability was proportional to abrasiveness, and abrasivenessshould be increased in order to enhance cleanability. It was also foundthat calcium hydrogenphosphate anhydride samples having a density oflower than 2.650 g/cm³ were short or cleaning action.

EXAMPLE 5

A further clinical test was carried out to demonstrate how a dentifricecontaining the calcium hydrogenphosphate anhydride abrasive of theinvention is effective for making the tooth aesthetically white.

Using abrasives shown in Table 8 having substantially equal abrasivenessin order to avoid that differential abrasion might affect the evaluationof the whitening effect, toothpastes having the same formulation as usedin Example 3 were prepared and subjected to the same test as done inExample 3. The results, which are expressed as an average value for eachpanel, are shown in Table 9.

                                      TABLE 8                                     __________________________________________________________________________                                             Abrasivity                                           Average Average    Specific                                                                            on copper                                            agglomerate                                                                           crystallite                                                                         Density                                                                            surface                                                                             plate                                Abrasive        diameter* (μm)                                                                     size (Å)                                                                        (g/cm.sup.3)                                                                       area (m.sup.2 /g)                                                                   (mg)                                 __________________________________________________________________________    G:                                                                              calcium hydrogenphosphate                                                                   10      1600  2.810                                                                              8.9   4.7   Invention                        anhydride No. 18                                                            H:                                                                              calcium hydrogenphosphate                                                                   25       230  2.615                                                                              28.6  1.3   Comparison                       anhydride No. 16                                                            I:                                                                              calcium hydrogenphosphate                                                                    2      4150  2.890                                                                              4.4   17.3  "                                anhydride No. 3                                                             __________________________________________________________________________     *Average agglomerate diameter was measured using a particle size              distribution measuring instrument, Microtrac (trade name, available from      Leed & Northrup Company).                                                

                  TABLE 9                                                         ______________________________________                                        Abrasive Before use    After use                                                                              Difference                                    ______________________________________                                        G        1.72          0.91     0.81                                          H        1.72          1.53     0.19                                          I        1.76          1.53     0.23                                          ______________________________________                                    

The data in Table 9 prove that the abrasives of the invention having adensity within the range of 2.650 to 2.885 g/cm³ as exemplified byabrasive G have improved whitening effect.

EXAMPLE 6

A variety of calcium hydrogenphosphate samples shown in Table 10 weremeasured for abrasiveness and cleanability by the same methods as usedin Example 1 in order to establish the correlation between physicalproperties and performance. The results are shown in Table 10.

                  TABLE 10                                                        ______________________________________                                        Abrading and cleaning properties of various                                   calcium hydrogenphosphate samples                                                       Mixing  Abrasion   Clean-                                           Sample    ratio   (RDA value)                                                                              ability                                          ______________________________________                                        DCP-D No. 2                                                                             --       57        2.6    Comparison                                DCP-A No. 3                                                                             --      135        4.3    "                                         DCP-A No. 4                                                                             --      ≧250                                                                              7.3    "                                         DCP-D No. 2/                                                                            8/2     140        4.5    "                                         DCP-A No. 4                                                                   DCP-D No. 2/                                                                            5/5     218        6.0    "                                         DCP-A No. 4                                                                   DCP-A No. 21                                                                            --       99        4.5    Invention                                 DCP-A No. 22                                                                            --      121        5.8    "                                         DCP-A No. 23                                                                            --      145        7.0    "                                         DCP-A No. 24                                                                            --      174        6.6    "                                         DCP-D No. 2/                                                                            5/5     130        6.6    "                                         DCP-A No. 23                                                                  DCP-D No. 2/                                                                            9/1      73        4.3    "                                         DCP-A No. 23                                                                  DCP-D No. 2/                                                                            5/5     140        6.1    "                                         DCP-A No. 24                                                                  ______________________________________                                    

The calcium hydrogenphosphate samples in Table 10 have physicalproperties and structure shown in Table 11-13.

                  TABLE 11                                                        ______________________________________                                        DCP-D: calcium hydrogenphosphate dihydrate                                               Average agglomerate                                                                          Specific surface                                    Sample No. diameter (μm)                                                                             area (m.sup.2 /g)                                   ______________________________________                                        2          14             1.1                                                 ______________________________________                                    

                                      TABLE 12                                    __________________________________________________________________________    DCP-A: calcium hydrogenphosphate anhydride (prior art)                              Average Specific   Average                                                                             Average                                              agglomerate                                                                           surface                                                                             Density                                                                            crystallite                                                                         primary particle                               Sample No.                                                                          diameter (μm)                                                                      area (m.sup.2 /g)                                                                   (g/cm.sup.3)                                                                       size (Å)                                                                        size (μm)                                   __________________________________________________________________________    3      2*     4.4   2.89 4150  1.5                                            4     16      1.2   2.89 4150  about 10                                       __________________________________________________________________________     *obtained by sieving a prior art DCPA and collecting a fraction having an     average agglomerate diameter of 2 microns.                               

                                      TABLE 13                                    __________________________________________________________________________    DCP-A: calcium hydrogenphosphate anhydride (invention)                              Average Specific   Average                                                                             Average                                              agglomerate                                                                           surface                                                                             Density                                                                            crystallite                                                                         primary particle                               Sample No.                                                                          diameter (μm)                                                                      area (m.sup.2 /g)                                                                   (g/cm.sup.3)                                                                       size (Å)                                                                        size (μm)                                   __________________________________________________________________________    21    3.5     3.5   2.80 1630  1.2                                            22    8       3.0   2.85 2510  1.0                                            23    13      3.8   2.87 3040  1.2                                            24    22      11.3  2.75  910  0.2                                            __________________________________________________________________________

It should be noted for the data of Tables 11-13 that the averageagglomerate diameter was measured using a particle size distributionmeasuring instrument, Microtrac (trade name, available from Leed &Northrup Company), the specific surface area was measured by the BETmethod, and the density was measured using a pycnometer followed bycalculation according to the above-described equation. The averagecrystallite size was measured in the same manner as in Example 1. Theprimary particle size was obtained on the basis of an electronmicrophotograph by selecting about 100 representative primary particlesrelatively facing to the front, measuring the longitudinal andtransverse dimensions of each particle, and calculating an arithmeticmean of them.

In FIG. 9, the abrasion (RDA value) is plotted relative to thecleanability of each abrasive. The reference numerals in the figurecorrespond to the sample Nos. in Table 10. Those reference numeralssurrounded by a circle are of the present invention.

As seen from the data of Table 10 and FIG. 9, in the case of the priorart calcium hydrogenphosphate dihydrate and calcium hydrogenphosphateanhydride samples, cleanability is proportional to abrasiveness, andabrasiveness must be increased in order to enhance cleanability.Conversely, the calcium hydrogenphosphate anhydride samples of thepresent invention were found to exhibit enhanced cleanabilityirrespective of low abrasiveness. It was also found that a mixture ofcalcium hydrogenphosphate dihydrate and calcium hydrogenphosphateanhydride of the invention had a similar effect.

EXAMPLE 7

Four toothpastes having the following formulations J, K, L, and M wereprepared, and examined for juice effect and favorableness in thefollowing manner using a sensory panel of 10 members. The results areshown in Table 14.

    ______________________________________                                        Formulation J          % by weight                                            ______________________________________                                        Propylene glycol       2.0                                                    Sodium carboxymethyl cellulose                                                                       1.0                                                    Glycerin               20.0                                                   Sodium saccharin       0.2                                                    Colloidal silica       2.0                                                    Flavors                1.0                                                    Calcium hydrogenphosphate dihydrate                                                                  24.0                                                   Sodium lauryl sulfate  1.5                                                    Calcium hydrogenphosphate anhydride                                                                  24.0                                                   No. 25* (present invention)                                                   Water                  Balance                                                Total                  100.0%                                                 ______________________________________                                         *average agglomerate diameter 18.3 μm;                                     specific surface area 3.1 m.sup.2 /g;                                         density 2.86 g/cm.sup.3 ;                                                     average crystallite size 2870Å; and                                       average primary particle size 1.1 μm                                  

Formulation K

This is the same as formulation J except that 24.0% of calciumhydrogenphosphate anhydride No. 25 of the present invention is replacedby 24.0% of a prior art calcium hydrogenphosphate anhydride No. 4(average agglomerate diameter 16.1 μm; specific surface area 1.2 m² /g;density 2.89 g/cm³ ; average crystallite size 4150 Å; and averageprimary particle size about 10 μm).

Formulation L

This is the same as formulation K except that 0.5% of sodium N-lauroylsarcosinate is further added.

Formulation M

This is the same as formulation K except that 1.5% of sodium laurylsulfate is replaced by 1.5% of α-olefin sulfonate.

Juice Effect Measurement

Ten panel members held one-half cup of noncarbonated, pure orange juicein their mouth some time and then swallowed it down such that theyperceived the taste or feel of the juice. Then, they brushed their toothwith the above-prepared toothpaste, and drank the same cup of juice inthe same manner as above one minute after the tooth-brushing. A changeof taste was evaluated in accordance with the following criterion. Theresults, which are expressed as a total of the respective points thatten members gave for each toothpaste, are shown in Table 14.

    ______________________________________                                        Evaluation criterion                                                          ______________________________________                                         0:            no change                                                      -1:            taste changed rather worse                                     -2:            taste changed very worse                                       ______________________________________                                    

Favorableness Measurement

Using a panel of 10 members, sensory evaluation was made by Scheffe'spair comparison procedure in accordance with the following criterion.

    ______________________________________                                        Evaluation criterion                                                                   As compared with the former toothpaste                                        used in brushing, the latter toothpaste is                           ______________________________________                                        +2:        much favorable.                                                    +1:        appreciably favorable.                                              0:        equally favorable.                                                 -1:        somewhat unfavorable.                                              -2:        strongly unfavorable.                                              ______________________________________                                    

                  TABLE 14                                                        ______________________________________                                        Formulation                                                                            Juice effect                                                                             Favorableness                                             ______________________________________                                        J        -1         +0.325       Invention                                    K        -13        -0.610       Comparison                                   L        -6         -0.055       "                                            M        -2         +0.340       "                                            ______________________________________                                    

The data of Table 14 prove that the toothpaste containing the abrasiveof the present invention exhibits improved juice effect and gives apleasant feel to the mouth. That is, the toothpaste of formulation Jhaving the abrasive of the invention blended therein is significantlyimproved in juice effect and more favored than that of formulation Khaving prior art calcium hydrogenphosphate anhydride blended therein andthat of formulation L having N-lauroylsarcosinate blended in formulationK, and substantially equivalent in juice effect and favorableness tothat of formulation M having α-olefin sulfonate blended therein as afoaming agent.

EXAMPLE 8

A variety of calcium hydrogenphosphate samples having substantiallyequal average agglomerate diameter were tested for enamel scratchinessby the following method. By the enamel scratchiness used herein is meantthe tendency that calcium hydrogenphosphate particles will formscratches in the dental enamel during brushing. The calciumhydrogenphosphate samples used are samples identified as No. 2, No. 4,No. 23, and No. 2/No. 4 (8/2) mixture in Table 10.

Enamel Scratchiness Measurement

A bovine tooth piece cut to a size of 5 mm×5 mm was embedded in a resin,and the bovine tooth enamel was ground to a smooth surface by means of arotary grinder, and then polished with a No. 1200 emery paper, polishedwith titanium dioxide grits, and buff polished to a gloss of 100±3.0 asmeasured by a gloss meter (GLOSS METER VG-10, manufactured by NihonDenshoku Kogyo K.K.). The gloss of 100 means that the enamel surface isa glossy surface essentially free of defects.

The bovine tooth piece was then mounted in a polishing tank of ahorizontal abrasion tester, into which was poured a suspension of 5grams of a powder (each of calcium hydrogenphosphate samples shown inTable 15) in 15 grams of an aqueous solution of 60% glycerin containing0.3% of sodium carboxymethyl cellulose. The bovine tooth piece wasbrushed 2000 strokes for 12 minutes in the tester under a load of 200grams. The brush used was the same as used in Example 1. At the end ofbrushing, the gloss of the tooth surface was measured by the glossmeter. The difference between the initial and final gloss values (orgloss reduction) is determined for evaluation of scratchiness. Thesmaller the gloss reduction, the lower is the scratchiness.

                  TABLE 15                                                        ______________________________________                                        Calcium                                                                       hydrogenphosphate                                                             sample No.  Abrasiveness                                                                             Gloss                                                  in Table 10 (RDA value)                                                                              reduction                                              ______________________________________                                        DCP-A No. 23                                                                              145        -2.1 ± 1.8                                                                            Invention                                   DCP-A No. 4 ≧250                                                                              -20.5 ± 3.5                                                                           Comparison                                  DCP-D No. 2/                                                                              140        -6.4 ±2.6                                                                             "                                           DCP-A No. 4(8/2)                                                              DCP-D No. 2  57        -0.1 ± 2.9                                                                            "                                           ______________________________________                                    

As seen from the data of Table 15, the calcium hydrogenphosphateanhydride abrasive of the invention is sufficiently low in scratchinessand causes little damage to the dental enamel. More specifically, theabrasive of the invention identified as DCP-A No. 23 exhibits extremelylow scratchiness irrespective of substantially the same abrasiveness ascompared with the prior art calcium hydrogenphosphate dihydrate andanhydride samples.

EXAMPLE 9

The abrasiveness and cleanability of various calcium hydrogenphosphatesamples were determined by the same methods as in Example 4 to establishthe correlation between physical properties and performance. The resultsare shown in Table 16.

                  TABLE 16                                                        ______________________________________                                        Abrasivity on copper plate and cleanability                                   of various calcium hydrogenphosphate samples                                            Mixing                                                                        ratio by Abrasivity                                                                              Clean-                                           Sample    weight   (mg)      ability                                          ______________________________________                                        DCP-D No. 1                                                                             --       0.8       2.3    Comparison                                DCP-D No. 2                                                                             --       1.2       2.5    "                                         DCP-A No. 3                                                                             --       17.3      4.3    "                                         DCP-A No. 4                                                                             --       47.0      7.3    "                                         DCP-D No. 2/                                                                            8/2      18.5      4.5    "                                         DCP-A No. 4                                                                   DCP-D No. 2/                                                                            5/5      31.4      6.0    "                                         DCP-A No. 4                                                                   DCP-A No. 26                                                                            --       1.2       4.4    Invention                                 DCP-A No. 27                                                                            --       2.1       5.2    "                                         DCP-A No. 28                                                                            --       16.4      6.3    "                                         DCP-A No. 29                                                                            --       19.0      5.8    "                                         DCP-D No. 2/                                                                            5/5      1.2       4.0    "                                         DCP-A No. 26                                                                  DCP-D No. 2/                                                                            8/2      7.1       4.9    "                                         DCP-A No. 28                                                                  DCP-D No. 2/                                                                            5/5      14.9      6.0    "                                         DCP-A No. 28                                                                  ______________________________________                                    

The calcium hydrogenphosphate samples in Table 16 have averageagglomerate diameter, average crystallite size, density, specificsurface area, and average roundness shown in Tables 17-19.

                  TABLE 17                                                        ______________________________________                                        DCP-D: calcium hydrogenphosphate dihydrate                                            Average agglomerate                                                                          Specific surface                                                                          Average                                    Sample No.                                                                            diameter (μm)                                                                             area (m.sup.2 /g)                                                                         roundness                                  ______________________________________                                        1        9             1.2         0.38                                       2       14             1.1         0.36                                       ______________________________________                                    

                  TABLE 18                                                        ______________________________________                                        DCP-A: platy, angular calcium hydrogenphosphate anhydride                           Average    Average         Specific                                           agglomerate                                                                              crystal-        surface                                                                              Average                               Sample                                                                              diameter   lite     Density                                                                              area   round-                                No.   (μm)    size (Å)                                                                           (g/cm.sup.3)                                                                         (m.sup.2 /g)                                                                         ness                                  ______________________________________                                        3      2*        4150     2.890  4.4    0.41                                  4     16         4150     2.890  1.2    0.40                                  ______________________________________                                         *obtained by sieving prior art DCPA and collecting a fraction having an       average agglomerate diameter of 2 microns.                               

                  TABLE 19                                                        ______________________________________                                        DCP-A: spherulitic calcium hydrogenphosphate anhydride                              Average    Average         Specific                                           agglomerate                                                                              crystal-        surface                                                                              Average                               Sample                                                                              diameter   lite     Density                                                                              area   round-                                No.   (μm)    size (Å)                                                                           (g/cm.sup.3)                                                                         (m.sup.2 /g)                                                                         ness                                  ______________________________________                                        26    17          710     2.70   15.0   0.85                                  27    22         1860     2.85   9.1    0.70                                  28    14         2030     2.87   5.0    0.60                                  29     8         2250     2.88   3.6    0.51                                  ______________________________________                                    

It should be noted for the data of Tables 17-19 that the averageagglomerate diameter was measured using a particle size distributionmeasuring instrument, Microtrac (trade name, available from Leed &Northrup Company), and the specific surface area was measured by the BETmethod.

In FIG. 10, the abrasivity on a copper plate brushed with each abrasiveis plotted relative to the cleanability of the abrasive. The referencenumerals in the figure correspond to the numbers in Table 16. Thosereference numerals surrounded by a circle are of the present invention.

As seen from the data of Table 16 and FIG. 10, in the case of the priorart calcium hydrogenphosphate dihydrate and subangular calciumhydrogenphosphate anhydride samples, cleanability is proportional toabrasiveness, and abrasiveness must be increased in order to enhancecleanability. Conversely, the spherulitic calcium hydrogenphosphateanhydride samples of the present invention were found to exhibitenhanced cleanability independent of abrasiveness, or irrespective oflow abrasiveness. The abrasives of the present invention are comparablein cleanability to prior art abrasives having an abrasivity of about 20to 30 mg when they have an abrasivity of about 1 to 5 mg, and to priorart abrasives having an abrasivity of about 30 to 50 mg when they havean abrasivity of about 5 to 20 mg. It was also found that a mixture ofcalcium hydrogenphosphate dihydrate and spherulitic calciumhydrogenphosphate anhydride in a weight ratio of 5:5 had a similareffect.

EXAMPLE 10

A variety of calcium hydrogenphosphate samples having substantiallyequal average agglomerate diameter were determined for abrasiveness andgloss increase. The abrasiveness expressed as an abrasivity on a copperplate was measured in the same manner as in Example 4 while the glossincrease was measured in the following manner. The results are shown inTable 20.

Gloss Increase Measurement

A bovine tooth piece cut to a size of 5 mm×5 mm was embedded in a resin,and the bovine tooth enamel was ground to a smooth surface by means of arotary grinder, and thereafter polished with a No. 1200 emery paper,polished with calcium hydrogenphosphate anhydride, and then buffpolished to a gloss of 80.0±2.0 as measured by a gloss meter (GLOSSMETER VG-10, manufactured by Nihon Denshoku Kogyo K.K.).

The thus polished bovine tooth piece was then mounted in a polishingtank of a horizontal abrasion tester, into which was poured a suspensionof 5 grams of a powder (each of calcium hydrogenphosphate samples shownin Table 20) in 15 grams of an aqueous solutin of 60% glycerincontaining 0.3% of sodium carboxymethyl cellulose. The bovine toothpiece was brushed 7000 strokes for 40 minutes in the tester under a loadof 200 grams. The brush used was the same as used in Example 1. At theend of brushing, the gloss of the tooth surface was measured by thegloss meter. The difference between the initial and final gloss valuesis determined as a gloss increase.

                  TABLE 20                                                        ______________________________________                                               Average     Average  Abrasi-                                                  agglomerate round-   vity  Gloss                                       Sample diameter (μm)                                                                          ness     (mg)  increase                                    ______________________________________                                        DCP-D  14          0.36     1.2   +4.0   Com-                                 No. 2                                    parison                              DCP-A  17          0.85     1.2    +11.5 In-                                  No. 26                                   vention                              ______________________________________                                    

As seen from the data of Table 20, the spherulitic calciumhydrogenphosphate anhydride sample of the present invention can greatlyimprove the gloss of tooth surface irrespective of substantially thesame abrasiveness as compared with the prior art calciumhydrogenphosphate dihydrate.

EXAMPLE 11

Two toothpastes having the following formulation were prepared andexamined whether they are favored or not by a sensory panel of 20memers. The results are shown in Table 21.

    ______________________________________                                        Formulation          % by weight                                              ______________________________________                                        Propylene glycol     2.5                                                      Sodium carboxymethyl cellulose                                                                     1.2                                                      Glycerin             25.0                                                     Sodium saccharin     0.1                                                      Colloidal silica     2.0                                                      Flavors              1.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Magnesium tertiary phosphate                                                                       2.0                                                      octahydrate                                                                   Abrasive shown in Table 21                                                                         40.0                                                     Preservative         trace amount                                             Water                balance                                                  Total                100.0%                                                   ______________________________________                                    

                  TABLE 21                                                        ______________________________________                                                    Number of panel members                                                     Mixing  favor-  Unfavor-                                                                             No differ-                                   Abrasive  ratio   able    able   ence                                         ______________________________________                                        DCP-D No. 2/                                                                            5/5      6      7      7       Com-                                 DCP-A No. 4                              parison                              DCP-D No. 2/                                                                            5/5     13      3      4       In-                                  DCP-A No. 28                             vention                              ______________________________________                                         Note:                                                                         The tests total to 40 since the order effect is taken into account, that      is, one toothpaste is followed by the other in the first test and the         other is followed by the one in the second test.                         

As seen from the data of Table 21, the toothpaste having the spheruliticcalcium hydrogenphosphate anhydride abrasive blended therein is morefavorable than the toothpaste having the prior art calciumhydrogenphosphate anhydride abrasive blended therein. Fourteen membersamong 20 panel members reported that the former toothpaste is milder tothe mouth. That is, the spherulitic calcium hydrogenphosphate anhydrideabrasive of the present invention is improved in oral cavity cleaningaction and gives a more pleasant feel to the mouth irrespective of lowabrasiveness as compared with the prior art calcium hydrogenphosphateanhydride abrasive.

Examples of toothpastes containing calcium hydrogenphosphate anhydrideabrasives according to the present invention are shown below.

All of the toothpastes shown in Examples were prepared by mixing thecalcium hydrogenphosphate anhydride abrasive with the other ingredients.

EXAMPLE 12

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 40.0%                                                   Propylene glycol     2.0                                                      Glycerin             30.0                                                     Sodium carboxymethyl cellulose                                                                     1.3                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.2                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        11.0   μm                                            Average crystallite size                                                                            620    Å                                            Density               2.69   g/cm.sup.3                                       Specific surface area 15.3   m.sup.2 /g                                       Average roundness     0.87                                                

EXAMPLE 13

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 16.5%                                                   Calcium hydrogenphosphate dihydride                                                                23.5                                                     Propylene glycol     2.0                                                      Glycerin             10.0                                                     Sorbitol              10.0%                                                   Sodium carboxymethyl cellulose                                                                     0.7                                                      Carrageenan          0.3                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        22.0   μm                                            Average crystallite size                                                                            380    Å                                            Density               2.66   g/cm.sup.3                                       Specific surface area 19.0   m.sup.2 /g                                       Average roundness     0.90                                                

EXAMPLE 14

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 10.0%                                                   Aluminum hydroxide   30.0                                                     Propylene glycol     2.0                                                      Sorbitol             25.0                                                     Sodium carboxymethyl cellulose                                                                     1.2                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        11.0   μm                                            Average crystallite size                                                                            510    Å                                            Density               2.68   g/cm.sup.3                                       Specific surface area 15.8   m.sup.2 /g                                       Average roundness     0.87                                                

EXAMPLE 15

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 35.0%                                                   Calcium carbonate    30.0                                                     Propylene glycol     2.0                                                      Sorbitol             25.0                                                     Sodium carboxymethyl cellulose                                                                     1.1                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        7.3    μm                                            Average crystallite size                                                                            600    Å                                            Density               2.73   g/cm.sup.3                                       Specific surface area 14.9   m.sup.2 /g                                       Average roundness     0.84                                                

EXAMPLE 16

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 45%                                                     Propylene glycol     2.0                                                      Sorbitol             20                                                       Carrageenan          1.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sucrose monopalmitate                                                                              1.0                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Dextranase           2.0                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        7.3    μm                                            Average agglomerate diameter                                                                        700    Å                                            Density               2.78   g/cm.sup.3                                       Specific surface area 13.8   m.sup.2 /g                                       Average roundness     0.80                                                

EXAMPLE 17

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  40%                                                    Calcium hydrogenphosphate dihydride                                                                10                                                       Glycerin              15                                                      Sorbitol              10                                                      Sodium carboxymethyl cellulose                                                                     1.2                                                      Sodium lauryl sulfate                                                                              1.2                                                      Stevioside           0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Glycyrrhizin         0.1                                                      Sodium pyrophosphate  0.05                                                    Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        17.8   μm                                            Average crystallite size                                                                            500    Å                                            Density               2.73   g/cm.sup.3                                       Specific surface area 17.6   m.sup.2 /g                                       Average roundness     0.85                                                

EXAMPLE 18

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  25%                                                    Precipitated silica  8.0                                                      Glycerin              10                                                      Sorbitol              35                                                      Carbopol             0.5                                                      Polyvinyl pyrrolidone                                                                              0.1                                                      Sodium lauryl sulfate                                                                              0.7                                                      Sodium N--lauroylsarcosinate                                                                       0.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium phosphate     0.2                                                      Tranexamic acid      0.1                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        15.1   μm                                            Average crystallite size                                                                            430    Å                                            Density               2.73   g/cm.sup.3                                       Specific surface area 17.0   m.sup.2 /g                                       Average roundness     0.75                                                

EXAMPLE 19

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  30%                                                    Aluminum hydroxide    10                                                      Glycerin                5%                                                    Sorbitol              20                                                      Polyethylene glycol    5                                                      Xanthane gum         1.0                                                      Sodium lauryl sulfate                                                                              1.2                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Glycyrrhizin         0.1                                                      Lauroyl monoglyceride                                                                              0.1                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        22.1   μm                                            Average crystallite size                                                                            370    Å                                            Density               2.65   g/cm.sup.3                                       Specific surface area 19.0   m.sup.2 /g                                       Average roundness     0.75                                                

EXAMPLE 20

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 16.5%                                                   Calcium hydrogenphosphate dihydride                                                                23.5                                                     Propylene glycol     2.0                                                      Glycerin             10.0                                                     sorbitol             10.0                                                     Sodium carboxymethyl cellulose                                                                     0.7                                                      Carrageenan          0.3                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        22.1   μm                                            Average crystallite size                                                                            1750   Å                                            Density               2.84   g/cm.sup.3                                       Specific surface area 6.5    m.sup.2 /g                                       Average roundness     0.70                                                

EXAMPLE 21

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 10.0%                                                   Aluminum hydroxide   30.0                                                     Propylene glycol     2.0                                                      Sorbitol             25.0                                                     Sodium carboxymethyl cellulose                                                                     1.2                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        11.0   μm                                            Average crystallite size                                                                            1660   Å                                            Density               2.85   g/cm.sup.3                                       Specific surface area 5.5    m.sup.2 /g                                       Average roundness     0.71                                                

EXAMPLE 22

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  45%                                                    Propylene glycol     2.0                                                      Sorbitol              20                                                      Carrageenan          1.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sucrose monopalmitate                                                                              1.0                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Dextranase           2.0                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        8.6    μm                                            Average crystallite size                                                                            2365   Å                                            Density               2.87   g/cm.sup.3                                       Specific surface area 3.5    m.sup.2 /g                                       Average roundness     0.61                                                

EXAMPLE 23

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  40%                                                    Calcium hydrogenphosphate dihydride                                                                 10                                                      Glycerin              15                                                      Sorbitol              10                                                      Sodium carboxymethyl cellulose                                                                     1.2                                                      Sodium lauryl sulfate                                                                              1.2                                                      Stevioside           0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Glycyrrhizin         0.1                                                      Sodium pyrophosphate  0.05                                                    Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anyhdride:                           Average agglomerate diameter                                                                        17.8   μm                                            Average crystallite size                                                                            870    Å                                            Density               2.75   g/cm.sup.3                                       Specific surface area 10.1   m.sup.2 /g                                       Average roundness     0.78                                                

EXAMPLE 24

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  25%                                                    Precipitated silica  8.0                                                      Glycerin              10                                                      Sorbitol              35                                                      Carbopol             0.5                                                      Polyvinyl pyrrolidone                                                                              0.1                                                      Sodium lauryl sulfate                                                                              0.7                                                      Sodium N--lauroylsarcosinate                                                                       0.5                                                      Sodium Saccharin     0.1                                                      Flavor               1.0                                                      Sodium phosphate     0.2                                                      Tranexamic acid      0.1                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        15.1   μm                                            Average crystallite size                                                                            3190   Å                                            Density               2.88   g/cm.sup.3                                       Specific surface area 2.8    m.sup.2 /g                                       Average roundness     0.58                                                

EXAMPLE 25

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 40.0%                                                   Propylene glycol     2.0                                                      Glycerin             30.0                                                     Sodium carboxymethyl cellulose                                                                     1.3                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.2                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        15.1   μm                                            Average crystallite size                                                                            650    Å                                            Density               2.70   g/cm.sup.3                                       Specific surface area 13.0   m.sup.2 /g                                       Average roundness     0.81                                                

EXAMPLE 26

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 16.5%                                                   Calcium hydrogenphosphate dihydride                                                                23.5                                                     Propylene glycol     2.0                                                      Glycerin             10.0                                                     Sorbitol             10.0                                                     Sodium carboxymethyl cellulose                                                                      0.7%                                                    Carrageenan          0.3                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        11.0   μm                                            Average crystallite size                                                                            1510   Å                                            Density               2.80   g/cm.sup.3                                       Specific surface area 8.0    m.sup.2 /g                                       Average roundness     0.65                                                

EXAMPLE 27

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 10.0%                                                   Aluminum hydroxide   30.0                                                     Propylene glycol     2.0                                                      Sorbitol             25.0                                                     Sodium carboxymethyl cellulose                                                                     1.2                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin      0.1%                                                    Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        22.1   μm                                            Average crystallite size                                                                            430    Å                                            Density               2.67   g/cm.sup.3                                       Specific surface area 18.1   m.sup.2 /g                                       Average roundness     0.85                                                

EXAMPLE 28

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 35.0%                                                   Calcium carbonate    10.0                                                     Propylene glycol     2.0                                                      Sorbitol             25.0                                                     Sodium carboxymethyl cellulose                                                                     1.1                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Perservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        7.3    μm                                            Average crystallite size                                                                            2100   Å                                            Density               2.83   g/cm.sup.3                                       Specific surface area 6.1    m.sup.2 /g                                       Average roundness     0.68                                                

EXAMPLE 29

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  45%                                                    Propylene glycol     2.0                                                      Sorbitol              20                                                      Carrageenan          1.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sucrose monopalmitate                                                                              1.0                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Dextranase           2.0                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        17.8   μm                                            Average crystallite size                                                                            1080   Å                                            Density               2.75   g/cm.sup.3                                       Specific surface area 8.9    m.sup.2 /g                                       Average roundness     0.73                                                

EXAMPLE 30

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  40%                                                    Calcium hydrogenphosphate dihydride                                                                 10                                                      Glycerin              15                                                      Sorbitol              10                                                      Sodium carboxymethyl cellulose                                                                     1.2                                                      Sodium lauryl sulfate                                                                              1.2                                                      Stevioside           0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Glycyrrhizin         0.1                                                      Sodium pyrophosphate  0.05                                                    Water                Balance                                                                      100.0%                                                                              by weight                                           ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        22.1   μm                                            Average crystallite size                                                                            430    Å                                            Density               2.67   g/cm.sup.3                                       Specific surface area 18.1   m.sup.2 /g                                       Average roundness     0.85                                                

EXAMPLE 31

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  25%                                                    Precipitated silica   10                                                      Glycerin              10                                                      Sorbitol              35                                                      Carbopol              0.5%                                                    Polyvinyl pyrrolidone                                                                              0.1                                                      Sodium lauryl sulfate                                                                              0.7                                                      sodium N--lauroylsarcosinate                                                                       0.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Tranexamic acid      0.1                                                      Sodium phosphate     0.2                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        7.3    μm                                            Average crystallite size                                                                            2100   Å                                            Density               2.83   g/cm.sup.3                                       Specific surface area 4.3    m.sup.2 /g                                       Average roundness     0.68                                                

EXAMPLE 32

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  30%                                                    Aluminum hydroxide    10                                                      Glycerin               5                                                      Sorbitol              20                                                      Polyethylene glycol    5                                                      Xanthane gum         1.0                                                      Sodium lauryl sulfate                                                                              1.2                                                      Sodium saccharin      0.1%                                                    Flavor               1.0                                                      Glycyrrhizin         0.1                                                      Lauroyl monoglyceride                                                                              0.1                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        11.0   μm                                            Average crystallite size                                                                            1360   Å                                            Density               2.78   g/cm.sup.3                                       Specific surface area 8.0    m.sup.2 /g                                       Average roundness     0.70                                                

EXAMPLE 33

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 40.0%                                                   Propylene glycol     2.0                                                      Glycerin             30.0                                                     Sodium carboxymethyl cellulose                                                                     1.3                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.2                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        15.1   μm                                            Average crystallite size                                                                            830    Å                                            Density               2.70   g/cm.sup.3                                       Specific surface area 13.2   m.sup.2 /g                                       Average roundness     0.80                                                

EXAMPLE 34

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 16.5%                                                   Calcium hydrogenphosphate dihydride                                                                23.5                                                     Propylene glycol     2.0                                                      Glycerin             10.0                                                     Sorbitol             10.0                                                     Sodium carboxymethyl cellulose                                                                     0.7                                                      Carrageenan          0.3                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        10.0   μm                                            Average crystallite size                                                                            2930   Å                                            Density               2.88   g/cm.sup.3                                       Specific surface area 4.7    m.sup.2 /g                                       Average roundness     0.65                                                

EXAMPLE 35

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 10.0%                                                   Aluminum hydroxide   30.0                                                     Propylene glycol     2.0                                                      Sorbitol             25.0                                                     Sodium carboxymethyl cellulose                                                                     1.2                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        7.3    μm                                            Average crystallite size                                                                            2100   Å                                            Density               2.83   g/cm.sup.3                                       Specific surface area 6.1    m.sup.2 /g                                       Average roundness     0.68                                                

EXAMPLE 36

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 35.0%                                                   Calcium carbonate    10.0                                                     Propylene glycol     2.0                                                      Sorbitol             25.0                                                     Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        20.4   μm                                            Average crystallite size                                                                            330    Å                                            Density               2.65   g/cm.sup.3                                       Specific surface area 15.4   m.sup.2 /g                                       Average roundness     0.88                                                

EXAMPLE 37

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  45%                                                    Propylene glycol     2.0                                                      Sorbitol              20                                                      Carrageenan          1.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sucrose monopalmitate                                                                              1.0                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Dextranase           2.0                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        14.0   μm                                            Average crystallite size                                                                            2850   Å                                            Density               2.86   g/cm.sup.3                                       Specific surface area 3.0    m.sup.2 /g                                       Average roundness     0.66                                                

EXAMPLE 38

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  40%                                                    Calcium hydrogenphosphate dihydride                                                                 10                                                      Glycerin              15                                                      Sorbitol              10                                                      Sodium carboxymethyl cellulose                                                                     1.2                                                      Sodium lauryl sulfate                                                                               1.2%                                                    Stevioside           0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Glycyrrhizin         0.1                                                      Sodium pyrophosphate  0.05                                                    Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        23.1   μm                                            Average crystallite size                                                                            1080   Å                                            Density               2.75   g/cm.sup.3                                       Specific surface area 8.9    m.sup.2 /g                                       Average roundness     0.73                                                

EXAMPLE 39

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  25%                                                    Precipitated silica  8.0                                                      Glycerin              10                                                      Sorbitol              35                                                      Carbopol             0.5                                                      Polyvinyl pyrrolidone                                                                              0.1                                                      Sodium lauryl sulfate                                                                              0.7                                                      Sodium N--lauroylsarcosinate                                                                       0.5                                                      Sodium saccharin     0.1                                                      Flavor                1.0%                                                    Sodium phosphate     0.2                                                      Tranexamic acid      0.1                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        11.5   μm                                            Average crystallite size                                                                            1900   Å                                            Density               2.87   g/cm.sup.3                                       Specific surface area 5.3    m.sup.2 /g                                       Average roundness     0.60                                                

EXAMPLE 40

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                  30%                                                    Aluminum hydroxide    10                                                      Glycerin               5                                                      Sorbitol              20                                                      Polyethylene glycol    5                                                      Xanthane gum         1.0                                                      Sodium lauryl sulfate                                                                              1.2                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Glycyrrhizin         0.1                                                      Lauroyl monoglyceride                                                                              0.1                                                      Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        11.0   μm                                            Average crystallite size                                                                            1360   Å                                            Density               2.78   g/cm.sup.3                                       Specific surface area 8.0    m.sup.2 /g                                       Average roundness     0.70                                                

EXAMPLE 41

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 40.0%                                                   Propylene glycol     2.0                                                      Sorbitol             30.0                                                     Sodium carboxymethyl cellulose                                                                     1.0                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Magnesium tertiary phosphate                                                                       1.0                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        18.3   μm                                            Average crystallite size                                                                            2030   Å                                            Density               2.85   g/cm.sup.3                                       Specific surface area 5.3    m.sup.2 /g                                       Average primary particle size                                                                       0.8    μ m                                       

EXAMPLE 42

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 10.0%                                                   Calcium hydrogenphosphate dihydride                                                                37.0                                                     Propylene glycol     2.0                                                      Glycerin             25.0                                                     Sodium carboxymethyl cellulose                                                                     0.8                                                      Carrageenan          0.3                                                      Colloidal silica     1.5                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Magnesium tertiary phosphate                                                                       1.0                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        18.3   μm                                            Average crystallite size                                                                            2030   Å                                            Density               2.85   g/cm.sup.3                                       Specific surface area 5.3    m.sup.2 /g                                       Average primary particle size                                                                       0.8    μm                                        

EXAMPLE 43

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 21.0%                                                   Calcium hydrogenphosphate dihydride                                                                20.0                                                     Aluminum hydroxide   5.0                                                      Glycerin             20.0                                                     Polyethelene glycol  2.5                                                      Sodium carboxymethyl cellulose                                                                     0.7                                                      Carrageenan          0.4                                                      Colloidal silica     2.5                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium N--lauroylsarcosinate                                                                       0.5                                                      Sodium saccharin     0.1                                                      Magnesium tertiary phosphate                                                                       1.0                                                      Flavor               1.0                                                      Dextranase           2.0                                                      Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        18.3   μm                                            Average crystallite size                                                                            2030   Å                                            Density               2.85   g/cm.sup.3                                       Specific surface area 5.3    m.sup.2 /g                                       Average primary particle size                                                                       0.8    μm                                        

EXAMPLE 44

    ______________________________________                                        Calcium hydrogenphosphate anyhdride                                                                 10.0%                                                   Aluminum hydroxide   30.0                                                     Propylene glycol     2.5                                                      Glycerin             10.0                                                     Sorbitol             20.0                                                     Sodium carboxymethyl cellulose                                                                     1.0                                                      Carrageenan          0.2                                                      Colloidal silica     3.0                                                      Sodium lauryl sulfate                                                                              1.5                                                      Sodium saccharin     0.1                                                      Magnesium tertiary phosphate                                                                       1.0                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        18.3   μm                                            Average crystallite size                                                                            2030   Å                                            Density               2.85   g/cm.sup.3                                       Specific surface area 5.3    m.sup.2 /g                                       Average primary particle size                                                                       0.8    μm                                        

EXAMPLE 45

    ______________________________________                                        Calcium hydrogenphosphate anhydride                                                                 5.0%                                                    Calcium hydrogenphosphate dihydride                                                                40.0                                                     Propylene glycol     2.0                                                      Glycerin             15.0                                                     Sorbitol             20.0                                                     Sodium carboxymethyl cellulose                                                                     1.0                                                      Colloidal silica     2.0                                                      Sodium lauryl sulfate                                                                              1.0                                                      Sodium N--lauroylsarcosinate                                                                       0.5                                                      Sodium saccharin     0.1                                                      Flavor               1.0                                                      Sodium monofluorophosphate                                                                          0.76                                                    Preservative         Trace amount                                             Water                Balance                                                                       100.0% by weight                                         ______________________________________                                        *Properties of calcium hydrogenphosphate anhydride:                           Average agglomerate diameter                                                                        18.3   μm                                            Average crystallite size                                                                            2030   Å                                            Density               2.85   g/cm.sup.2                                       Specific surface area 5.3    m.sup.2 g                                        Average primary particle size                                                                       0.8    μm                                        

What is claimed is:
 1. A dentifrice composition comprising an abrasiveconsisting of calcium hydrogenphosphate anhydride whose crystallite hasan average size of 300 to 3,500 angstroms as measured by X-raydiffractometry.
 2. A dentifrice composition according to claim 1 whereinthe calcium hydrogenphosphate anhydride has a density of 2.650 to 2.885g/cm³, a specific surface area of 2.5 to 20 m² /g as measured by the BETmethod, and an average agglomerate diameter of 2 to 30 microns.
 3. Adentifrice composition according to claim 1 wherein the calciumhydrogenphosphate anhydride is in the form of a cohesive aggregate ofplate crystals whose primary particle has an average size of 0.1 to 5microns.
 4. A dentifrice composition according to claim 1 wherein thecalcium hydrogenphosphate anhydride is spherulitic.
 5. A dentifricecomposition according to claim 4 wherein the spherulitic calciumhydrogenphosphate anhydride has an average roundness of 0.45 to 0.9. 6.A dentifrice composition according to claim 2 wherein the calciumhydrogenphosphate anhydride is in the form of a cohesive aggregate ofplate crystals whose primary particle has an average size of 0.1 to 5microns.
 7. A dentifrice composition according to claim 2 wherein thecalcium hydrogenphosphate anhydride is spherulitic.
 8. A toothpastecomposition, comprising:5 to 95% by weight of the composition of acalcium hydrogenphosphate anhydride abrasive whose crystallite has anaverage size of 300 to 3,500 angstroms as measured by X-raydiffractometry wherein the calcium hydrogenphosphate anhydride has adensity of 2.650 to 2.885 g/cm³, a specific surface area of 2.5 to 20 m²/g as measured by the BET method, and an average agglomerate diameter of2 to 30 microns.
 9. A dentifrice composition according to claim 8,wherein said abrasive is present in an amount of 10 to 90% by weight ofthe composition.
 10. A method for cleaning teeth, comprising the stepsof: applying the dentifrice composition of claim 1 to a tooth surface;and scrubbing the tooth surface.
 11. A dentifrice composition,comprising;5 to 95% by weight of a calcium hydrogenphosphate anhydrideabrasive whose crystallite has an average size of 300 to 3,500 angstromsas measured by X-ray diffractometry; and at least one other ingredientselected from the group consisting of a binder, a humectant and aflavoring agent.
 12. A dentifrice composition according to claim 11,which contains 0.1 to 5% by weight of the composition of a binder.
 13. Adentifrice composition according to claim 11, which contains 1 to 70% byweight of the composition of a humectant.
 14. A dentifrice compositionaccording to claim 11, which contains 0.1 to 5% by weight of thecomposition of a flavoring agent.
 15. A dentifrice composition accordingto claim 11, which contains magnesium tertiary phosphate.
 16. Adentifrice composition according to claim 15, wherein said magnesiumtertiary phosphate is present in an amount of 0.1 to 5% by weight of thecomposition.